The wet gas gathering pipelines will produce natural gas hydrate with the condition of high pressure and low temperature, which may cause blockage of pipelines or failure of key control equipment. Adding alcohols Thermodynamic?Inhibitor(THI) is one of the feasible proposals to prevent hydrate formation. If the amount of THI is poured excessive, the costs of procurement, transportation, storage and water treatment will increase in large quantities. Therefore, it is significant to determine the minimum dosage of THI based on a reasonable safety margin. Calculation of THI injection dosage based on empirical formula method and phase equilibrium software, without considering the effect of flow. In this paper, a method coupling of phase equilibrium and flow was used to optimize the injection dosage of THI. Based on the OLGA component tracking model, the temperature, pressure and THI concentration along the line are tracked, and then the THI dosage was predicted more accurately. Taking the gas gathering pipeline of land and submarine as an example, different calculation methods were compared. The results show that the new method can reduce the THI consumption by more than 10%.

Combined with SEM, EDS, dynamic evaluation of plug formation, microscopic visualization and long core displacement experiments, the damage mechanism of residual acid in polymer injection oilfield to the reservoir was studied. The results show that the damage of residual acid to the reservoir is mainly due to the crosslinking point of the polymer molecular chain with high valence cations such as Al³⁺ and Fe³⁺ in residual acid. The crosslinking network elastic colloid is formed by the coordination between carboxylic acid radicals in the polymer side group and high valence cations, and the degree of crosslinking increases with the increase of ion concentration. The elastic colloid formed blocked at the edge and pit of the pore throat, which makes the pore throat diameter gradually smaller. In the process of flow, it wraps around the formation particles and carbonate sediments, forming a composite blockage micelle, resulting in deep plugging. The long core displacement experiment shows that residual acid can damage the core up to 60%. The research results provide a theoretical basis for the research and development of plugging removal fluid system and optimization of plug removal processes in polymer injection oilfield